KR101319441B1 - Leadframe - Google Patents

Abstract

According to the present invention, a metal substrate having an insulator groove on a lower surface thereof, having a die pad portion and a lead portion, a first lead plated on a portion of an upper surface of the lead portion, a second lead plated on a lower surface of the lead portion, and the insulation portion groove And an insulating part filling the gap, wherein the second lead is disposed at a distance closer to the die pad part than the first lead, and a distance between an upper surface of the die pad part and an upper surface of the insulating part is formed on the lead. A leadframe is provided that is smaller than the distance between the upper surface of the negative portion and the upper surface of the insulating portion.

Description

Leadframe {LEADFRAME}

The present invention relates to a leadframe.

In the manufacture of semiconductor packages, lead frames play an important role in supplying input / output means for chip mounting and signal transmission, and various types of lead frames are being developed for highly integrated signal transmission.

In general, the shape of a lead frame manufactured is a die pad and a lead portion using an etching method or a stamping method. However, the conventional method of manufacturing the lead frame is not easy to form a multi-row lead required for high integration of the semiconductor.

The conventional lead frame by two-stage etching implements a circuit pattern through a two-stage etching process with a half etching, and the lower end of the half-etched circuit pattern has been proposed a lead frame in the form of fixing with a polyimide resin film.

However, in the structure of the lead frame by the conventional two-stage etching, the implementation pitch of the circuit pattern is 120 micrometers, there is a limit in the micro-implementation has a disadvantage that the number of lead pin (lead pin) that can be implemented is limited.

In addition, the polyimide resin film supporting the lower end of the circuit pattern has a weak supporting force, and there is no special protective film on the upper part of the circuit pattern, resulting in weak stability in the assembly process.

In addition, according to the conventional method, in order to mount the lead frame on the PCB substrate, there is a process troublesome process of performing tin plating for soldering.

The present invention has been made to solve the above problems, an object of the present invention is to provide a more integrated signal transmission system, a frame with improved molding power through the surface roughness and a lead frame for implementing the same simpler process It is to provide a manufacturing method.

A lead frame according to an embodiment of the present invention has an insulation groove on a lower surface thereof, a metal substrate having a die pad portion and a lead portion, a first lead plated on a portion of an upper surface of the lead portion, and a plate on a lower surface of the lead portion. A second lead, and an insulating part filling the insulating part groove, wherein the second lead is disposed at a distance closer to the die pad part than the first lead, and between the top surface of the die pad part and the top surface of the insulating part. The distance is smaller than the distance between the top surface of the lead portion where the first lead is formed and the top surface of the insulation portion.

Surface roughness treatment may be implemented on at least one of the lead part, the first lead, the second lead, and the die pad part.

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The insulating part may have a structure overlapping an edge portion of the die pad metal layer on the lower surface of the second lead or the die pad part.

The thickness of the thickest portion of the die pad portion may be formed to be equal to or less than the thickness of the lead portion.

The first lead, the second lead, and the die pad metal layer may be formed of any one of Ni, Au, Pd, and Ag, or may be formed of a structure in which at least one or more of metal layers formed of two or more alloys are stacked.

The multi-row leadframe manufactured by the present invention can implement three or more rows of I / O pads, which are difficult to realize in existing leadframes, through the implementation of a fine circuit, and can increase molding power by forming an insulator under the leadframe. Surface roughness may be implemented on the surface of the material or the plating pattern to improve the bonding strength between the metal materials and the bonding strength with the molding material.

In particular, through the surface treatment process to enhance the surface roughness applied to the process, it is possible to enhance the adhesion between the metal member and the insulator, and the adhesion between the I / O pad, SMT pad and the metal member, The surface of the product having an increased roughness of the lead wire also increases the adhesion to the molding epoxy in the assembly process, thereby preventing delamination.

In addition, as the distance between the chip and the wire bonding part approaches from the microcircuit pattern implementation of the lead frame according to the present invention, the use of the wire is reduced and the cost is reduced. In addition, since the wire bonding pad can be connected to the outer lead under the microcircuit by etching, a large number of signal transmission systems can be established, and the process number is simpler and manufacturing cost is lower than that of BGA with similar structure. , Circuit, that is, the lead portion and the die pad surface, because the metal member is used as it is, excellent signal transmission and thermal conductivity. Furthermore, the thickness of the entire semiconductor package can be adjusted by adjusting the depth of the chip mounting portion by etching.

As a result, a fine lead pitch can be realized in a thick material, and since the lead wire thickness is implemented at the end of the process, the stability of the product is high with respect to the process during product progress as a whole.

1A and 1B show a manufacturing process diagram for the present invention.
FIG. 2 is a conceptual diagram illustrating process features applied to the process of FIGS. 1A and 1B according to the present invention.
Figure 3 shows another embodiment of the manufacturing process of the method of manufacturing a lead frame according to the present invention.
4 is a conceptual diagram illustrating process characteristics applied to the process of FIG. 3.
5 and 6 show another manufacturing process according to the present invention.
7 to 10 are conceptual diagrams for explaining the characteristics of the process according to the present invention.
11 and 12 illustrate a concept of providing surface roughness to the first lead, the second lead, and the die pad metal layer in the manufacturing process according to the present invention.
It is a top view of the lead frame which concerns on one Embodiment of this invention.

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration and operation according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description with reference to the accompanying drawings, the same reference numerals denote the same elements regardless of the reference numerals, and redundant description thereof will be omitted. The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

1. First Embodiment

1A and 1B show a manufacturing process diagram for the present invention.

Both surfaces of the metal substrate are plated to form a first lead, a second lead, and a die pad metal layer, an exposed surface of the bottom surface of the metal substrate is etched to form an insulating groove, and an insulating material is filled in the insulating groove to fill the insulating portion. And forming a die pad portion and a lead portion shorted to each other by etching the upper surface of the metal substrate. Particularly, in the present invention, the first lead is formed to be disposed outside the second lead. It is characterized by. Here, the outer side means that the second lead is formed at a position closer to the die pad portion than the first lead portion.

In the process according to the present invention, the method may further include a step of subjecting the surface of the metal substrate to the surface roughening before or after the formation of the first lead and the second lead.

Looking at the manufacturing process according to the present invention described above with reference to Figures 1a and 1b in detail,

In step (a), the metal substrate 100 is prepared as a member that is the main body of the circuit implementation. Here, the metal substrate 100 is preferably Cu, but a metal member such as Cu alloy, Fe, or an alloy thereof, which may be conductive, may be used. In addition, although the thickness of the metal substrate 100 is recommended to use less than 5mil to form a thin film substrate, it is also possible to use a member of less than 10mil. In the step (a), a process of performing roughness treatment on the surface of the metal substrate 100 may be further added. Such surface roughness treatment is implemented to improve the adhesion in the subsequent photosensitive material coating or plating process.

Thereafter, in step (b), the photosensitive film 120 is applied to both surfaces of the metal substrate 100, and then exposed through the photomask 130 on which the pattern is formed. Here, the pattern of the photo mask 130 is then formed to conform to the wire bonding pad (see FIG. 13 (a)) and the solder mounting pad (see FIG. 13 (c)).

On the other hand, as in step (c), the photosensitive film is removed in the unexposed portion, and the metal substrate of the removed portion is exposed (the process may be performed to remove the exposed portion). In particular, the exposed portions here correspond to the portions where the first and second leads will be formed later.

Thereafter, as in step (d), the metal substrate 100 exposed on both sides is plated to form the first lead 110a, the second lead 110b, and the die pad metal part 115. In this case, in the preferred embodiment according to the present invention, the first lead 110a is formed in a structure arranged outside the second lead 110b. That is, unlike the conventional structure, the second lead 110b is disposed close to the portion where the die pad metal layer 115 is formed, and the first lead 110a on the metal substrate 100 is formed on the die pad metal layer ( 115) is formed in a structure that is disposed at a relatively longer distance than the second lead in the formed portion.

Here, the plating process is preferably Ni plating, and in addition, at least one of Au, Pd, Ag on Ni may be plated. The implementation of such a plating layer generally proceeds with electroplating, but electroless plating, or electroplating and electroless plating may be used in combination.

After the implementation of the wire bonding pad part (the first lead 110a and the solder mounting pad part (the second lead 110b and the die pad metal part 115) by plating, the photosensitive film 120 is removed, and then, the step (e) is performed. As shown in the drawing, the lower surface of the metal substrate is etched to form the insulation grooves s.

Specifically, in step (e), after the step (d), the photosensitive material is coated again to proceed to the next process, and the upper surface proceeds without a pattern, and the upper surface of the mask pattern of exposure proceeds without a pattern, and the lower surface of FIG. 13 (c) The pattern of is applied to implement the exposure mask pattern, and after removing the photosensitive material of the lighted part (or the part not receiving the light) and proceeding the etching as shown in (e) It has a structure that is The photosensitive material used in this process is not a problem when applying the liquid-type photosensitive film (LPR), but when using the film-type photosensitive film (DFR), the vacuum lamination progresses when the photosensitive film adhesion decreases due to the difference between the steps of the member and the plating layer. Therefore, it is preferable to aim at the improvement of adhesive force.

In this case, after forming the insulating groove (s) in the step (e), the surface of the metal substrate 100 and the first and second leads (110a, 110b), the die pad metal layer 115, the insulating groove (s) The process of forming the surface roughness on the entire surface of the) may be added. Further additionally after the surface roughness treatment is performed in step (a). Of course, if the surface roughness treatment step is not added in step (a), the surface roughness treatment may be performed in this step.

Subsequently, in steps (h) to (g), an insulation portion 130 such as epoxy processed on the lower surface of the metal substrate 100 and a metal layer 140 serving as a support layer are laid up. Apply heat and pressure and press it tightly. The insulation 130 may be drilled, lasered, or punched, and the processed cross section may have a hole formed therein, as shown in (f). c) corresponds to the SMT Pad part. Such insulation (epoxy) processing has the advantage of facilitating the etching process of the insulation (epoxy) to be carried out later.

Insulation used in the present invention may use an epoxy material in which glass fibers are embedded in order to increase the rigidity of the product made of PP (Prepreg), in this case SMT Pad using a drill method that is easy to remove the glass fibers Hole processing of the part was performed.

The thickness of the epoxy material used is determined by the etching depth of the lower surface etched in Fig. 13 (c). In this case, it is most preferable that the difference be less than ± 5 μm from the etching depth, and it is preferable not to use a material that differs by more than 10 μm if possible.

The used metal layer 140 serves as a pattern masking so that the plated SMT pad part can remove only the portion covered by the epoxy material, and at the same time, supports the member weakened by etching, thereby facilitating the subsequent process. The metal layer 140 may be used as an etchable metal material such as Cu, Al, Fe, etc., and the thickness used is not limited. In this embodiment, a member having a thickness of 20, 35, 70, 100, or 125 um is used, and a metal member of 100 um or more may be used for a desired pattern etching. Used metal members can be removed as needed after all processes have been completed.

Thereafter, in steps (h) to (i), only the epoxy and the metal layers are selectively etched and removed to completely expose the plated surfaces of the second lead and die pad metal layers formed on the bottom surface of the metal substrate 100. In particular, in this case, as shown in FIG. 10, the edge portions of the second lead and the die pad metal layers are left in a structure in which one portion overlaps so that the second lead and the die pad can be covered by the epoxy (insulation). It is more desirable to maintain a firm bonding force of the metal layer.

Subsequently, in step (j), the photosensitive film is coated, and the upper surface of the metal substrate is subjected to an exposure process without a pattern on the lower surface of the circuit pattern as shown in FIG. By proceeding, the lower part of the insulating part epoxy is exposed, thereby enabling the division of the members connected together, so that the division into the die pad part 101 and the two lead parts 102 is possible. Here, if the mask pattern used in the process (c) of FIG. 1 is applied to FIG. 13 (b) and the bottom surface is etched by applying the pattern of FIG. 13 (c), it is easy to implement a fine circuit pattern in a subsequent process.

FIG. 2 is a process feature applied to the process of FIGS. 1A and 1B according to the present invention, and in steps (a) or (e) of FIG. 1A, that is, before or after the formation of the first and second leads. The result of performing the process of forming the surface roughness on the metal substrate 100 or the first and second leads is shown.

That is, the rough Cu is plated on the entire surface of the member by increasing the surface roughness. This is because after the lower surface etching is performed in step (a) of FIG. 1a or step (e), before or after plating the wire bonding pad part and the solder mounting pad part (SMT pad part). You can proceed later.

This rough surface roughness is 100-400nm and its thickness can be 0.3 ~ 1.5um. Roughly formed surface roughness enhances the adhesion to the epoxy bonded to the lower surface portion, and the roughness of the upper lead wire is effective to prevent delamination by increasing the adhesion to the molding epoxy. In addition, the rough Cu plating before the wire bonding pad and the solder mounting pad portion (SMT pad portion) plating may increase the adhesion between the member and the plating pad and may also increase the surface roughness of the plating portion.

2. Second Embodiment

Figure 3 shows another embodiment of the manufacturing process of the method of manufacturing a lead frame according to the present invention.

The basic process is (a) etching the lower surface of the metal substrate 100 (b) to form the insulating groove (s) first, and in the step (c) ~ (d) to form the insulating portion 130 and the metal layer 140 After the process of laminating and crimping is performed, only the epoxy and the metal layers are selectively etched and removed to completely expose the lower surface of the metal substrate 100 in steps (e) to (f).

In this case, in the process of forming the insulating portion groove (s), after implementing the pattern to plate the die pad metal layer in the center, it is preferable to implement the pattern so that the second lead can be formed on both sides. Of course, in this case, a step of roughening the surface in step (a) or step (b) may be added.

Subsequently, in step (g), after forming the first lead 110a, the second lead 110b, and the die pad metal part 115 through plating as in steps (b) to (d) of FIG. In step (h), the upper surface of the metal substrate is etched 111 to expose the insulating material layer, thereby forming the die pad portion 101 and the lead portion 102 shorted to each other. In particular, in this case, the first lead 110a is formed to have a structure disposed outside the second lead 110b. That is, unlike the conventional structure, the second lead 110b is disposed close to the portion where the die pad metal layer 115 is formed, and the first lead 110a on the metal substrate 100 is the die pad metal layer. The portion 115 is formed to have a structure that is disposed at a relatively longer distance than the second lead.

The process of this embodiment is different from the first embodiment in that the lower insulating grooves are formed before the first lead 110a, the second lead 110b, and the upper and lower die pad metal portions 115 are formed. . In addition, in the second embodiment, a surface roughening process may be performed in steps (a) and (b) of FIG. 3, and FIG. 4 illustrates a result of performing such surface roughness treatment.

This rough surface roughness is 100-400nm and its thickness can be 0.3 ~ 1.5um. Roughly formed surface roughness enhances the adhesion to the epoxy bonded to the lower surface portion, and the roughness of the upper lead wire is effective to prevent delamination by increasing the adhesion to the molding epoxy. In addition, the rough Cu plating before the wire bonding pad and the solder mounting pad portion (SMT pad portion) may increase the adhesion between the member and the plating pad and may also increase the surface roughness of the plating portion. same.

3. Third Embodiment

5 shows another manufacturing process according to the present invention.

In the present exemplary embodiment, in the steps (a) to (d), the photosensitive material 120 is coated on the upper and lower surfaces of the metal substrate 100, and the photosensitive material 120 is disposed on the upper and lower surfaces of the metal substrate through an exposure mask m. A pattern is formed, and the first lead 110a, the second lead 110b, and the die pad metal part 115 are formed through plating, and the photosensitive material is peeled off. In particular, even in this case, unlike the conventional structure, the second lead 110b is disposed close to the portion where the die pad metal layer 115 is formed, and the first lead 110a on the metal substrate 100 is disposed. The die pad metal layer 115 may be disposed at a relatively longer distance than the second lead.

In this case, after the step (a) or (d), a step of performing roughness treatment on the surface of the metal substrate 100 may be further added. Such surface roughness treatment is implemented to improve the adhesion in the subsequent photosensitive material coating or plating process.

Subsequently, in step (e), the photosensitive material 120 is secondly applied, exposed and developed through a mask (m) to implement a pattern as in (f), and then, as in step (g), a metal substrate Both surfaces of the 100 are first etched.

In this case, it is important that the primary etching is such that the metal substrate 100 does not penetrate. This is because when the metal substrate 100 is drilled, the formation of a fine circuit that proceeds later may not proceed smoothly. As such, the thickness of the metal substrate 100 remaining after the upper and lower etching of the metal substrate 100 is preferably 10-30 μm. It may be less than 10um, but the puncture of the member may appear, so care should be taken during the etching process. In particular, in this step, the chip mounting groove is formed by etching a portion of the upper surface of the metal substrate 100 on which the chip is to be mounted. In particular, after the completion of the step (g), the surface of the metal substrate 100 where the etching is performed, the surface of the insulator groove, the surface of the upper first lead 110a, the die pad metal layer 115 and the second lead 110b are performed. Surface roughness treatment may be performed on the surface of the.

Subsequently, in steps (h) to (i) of FIG. 6, an insulating part 130 and a metal layer 140 are formed on the lower surface of the metal substrate 110, and the metal substrate 100 is formed in (j) to (k). Only the epoxy and metal layers are selectively etched away so as to be fully exposed to the plated surfaces of the second lead and die pad metal layers formed on the bottom surface of the substrate). Then, as in (l), the upper surface of the metal substrate is etched to separate the two lead portions 102 and the die pad portion 101.

In the third embodiment, a surface roughness treatment process may be added in the processes (a), (d), and (g). In addition, in the subsequent process, an additional secondary etching is performed on the portion etched on the metal substrate 100 in the process step (l) in the first etched portion on the metal substrate.

Not only can the thickness of the lead wire connecting the wire bonding portion and the solder mounting portion be thinned through the simultaneous etching of the portion of the metal substrate 100 which is pre-etched on the upper portion of the metal substrate 100, but also the etching of the member surface which is not etched. Enables fine circuit line width implementation. In particular, it is possible to implement a thin thickness of 5 ~ 10um as needed.

This is made possible by applying the pattern of FIG. 13 (a) to the upper surface mask pattern of the exposure that proceeds to make the structure as shown in FIG. 1 (c) described above. That is, the etching of Fig. 13 (a) or Fig. 13 (b) on the upper surface of the metal substrate can reduce the height of not only the lead wire but also the portion where the die chip is placed as shown in Fig. 7.

As a result, the thickness and line width of the lead wire, and the height of the die pad portion can be adjusted simply by adjusting the etching depth and the ratio of the preprocess. Such a process has an advantage that the lower etching is not required to be excessively performed in the previous process in order to implement a fine circuit pattern and lower the thickness of the lead wire.

The epoxy filled in the insulator groove in the lower portion of the metal substrate serves to support the divided lead wire later, and furthermore, the adhesion force with the molding material can be effectively maintained during molding after die chip mounting.

FIG. 8 is an implementation of the first and second etching processes of FIG. 7, to show that the thickness of the lead wire may be controlled by adjusting the etching depth. For example, suppose that the upper etch depth t1 is 30 um and the lower etched depth t2 is 65 um when using a 5 mil member. The member a1, which is protected by the photosensitive film and is not etched, is left at a thickness t3 of 60 um.

After the secondary etching proceeds in the process to a depth of 30 um, t1 depth is t4 and lead wire separation proceeds. At the same time, the thickness of the lead wire enables a thin lead with a thickness of 30 um from t3 to t5.

At the same time, as shown in Fig. 13B, the etching depth to the portion where the die chip is raised can be adjusted. That is, the die chip is placed on the etched portion, thereby making it possible to slim down the package, which can be thickened due to the use of a thick member.

In FIG. 10 (a), d1 is the bump diameter, d2 is the diameter of the exposed metal layer pattern, d3 is the diameter of the plating first and second lead or die pad metal layers, and d3 is larger than d1 and d2 as shown in the drawing. And d2 may be large or the same. Taking d1 smaller than d3 strengthens the bonding of the insulating portion and the member in such a way that the plating end portion enters the insulating portion as shown in FIG. 10 (b).

Taking d2 smaller than d3 is to prevent the inside epoxy from being damaged as the etching liquid penetrates into the metal layer during the epoxy etching. In addition, in order to proceed with a smooth epoxy etching, it is preferable that the epoxy thickness t6, which is the remaining insulating portion, does not exceed 20 μm, and it is most preferable to leave it below 5 μm (Fig. 10 (b)).

11 and 12 illustrate a concept of providing surface roughness to a plating pattern (a first lead, a second lead, and a die pad metal layer) used as a wire bonding pad and a solder mounting pad in a manufacturing process according to the present invention.

Basically, the plating pattern according to the present invention may be formed of any one of Ni, Au, Pd, Ag, or may be formed in a structure in which at least one or more layers of metal layers formed of two or more alloys are stacked.

In this case, various plating lamination patterns such as (a) to (f) may be implemented, and FIG. 12 illustrates a rough Ni plating process to give a separate surface roughness to the plating layer. Rough Ni plating exhibited a surface roughness of between 300 and 800 nm, and its thickness can be adjusted as needed from 0.3 to 1.2 um.

In the lead frames manufactured in the first to third embodiments described above, referring to the structures of FIGS. 1B, 3H, and 6L, the metal substrate 100 may be etched. Implemented through patterning, but consequently includes a lead portion 102 having an insulation groove in the lower portion.

In particular, in this case, the second lead formed on the lower surface of the lead part may have a structure in which it is disposed at a position adjacent to the die pad part 101 relative to the first lead 110a and d. In addition, the structure includes an insulating part 130 filled with the insulating part groove and supporting the lead part and the die pad part in a shorted state. Particularly, a preferred embodiment according to the present invention is the lead part, the first part. And surface roughness treatment on at least one of the second lead and the die pad unit.

Although described in the embodiments of each manufacturing process, in the structure having an epoxy filled in the insulating portion groove of the lead frame according to the present invention, the insulating portion, the edge of the die pad metal layer on the lower surface of the second lead or the die pad portion 10. The overlapping portion may be formed in the above-described structure, and in particular, the thickness of the thickest portion of the die pad portion may be formed in a structure in which at least one or more metal layers are formed to be less than or equal to the thickness of the lead portion.

In the foregoing detailed description of the present invention, specific examples have been described. However, various modifications are possible within the scope of the present invention. The technical spirit of the present invention should not be limited to the above-described embodiments of the present invention, but should be determined by the claims and equivalents thereof.

110: metal substrate
101: die pad portion
102: lead portion
110a: first lead
110b: second lead
115: die pad metal layer
130: insulation
140: metal layer

Claims (6)

A metal substrate having an insulating portion groove on a bottom surface thereof, the die pad portion and a lead portion;
A first lead plated on a portion of an upper surface of the lead portion;
A second lead plated on a lower surface of the lead portion; And
Insulating part filling the insulating part groove,
The second lead is disposed at a distance closer to the die pad portion than the first lead,
And a distance between an upper surface of the die pad portion and an upper surface of the insulation portion is smaller than a distance between an upper surface of the lead portion on which the first lead is formed and an upper surface of the insulation portion.
delete The method according to claim 1,
Surface roughness treatment is implemented on any one or more of the lead portion, the first lead, the second lead and the die pad portion.
The method according to claim 1,
The insulation portion,
The lead frame is formed of a structure overlapping the edge portion of the die pad metal layer on the lower surface of the second lead or the die pad portion.
The method according to claim 3,
And a thickness of the thickest portion of the die pad portion is less than or equal to the thickness of the lead portion.
The method of claim 4,
The first lead, the second lead and the die pad metal layer,
Lead frame formed of any one of Ni, Au, Pd, Ag, or a structure in which at least one or more layers of metal layers formed of two or more alloys are laminated.

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